Hello.
In case you're using our 5.x upstream repositories for Debian or Ubuntu,
as originally suggested on https://www.knot-resolver.cz/download/
<https://www.knot-resolver.cz/download/> you'll be running into an
expired signing key since yesterday. As we haven't updated in time
again, manual action is needed on every machine, I'm afraid.
Let's take this as an opportunity to migrate to our newer repositories
that should work better. You may already know them e.g. from version
6.x or Knot DNS. Setup is described at
https://pkg.labs.nic.cz/doc/?project=knot-resolver
<https://pkg.labs.nic.cz/doc/?project=knot-resolver>
You may want to also uninstall the original helper package by:
apt purge knot-resolver-release
Thanks for bearing with this inconvenience.
--Vladimir
